Valve for rock drills



Patented July 30, 1940 UNITED STATES,

Parent osrics VALVE FOR ROCK DRILLS William A. Smith, Jr., Cleveland,Ohio, assignor to The Cleveland Roch Drill Company, Cleveland, Ohio, acorporation .of Ohio Application June 19, 1939, Serial No. 279,786

6 Claims.

This invention relates broadly to fluid actuated rock drills, but moreparticularly to a valvular action of the motive fluid.

Another object of this invention is to produce a rock drill with valvescapable of rapid and eificient disposition of the motive fluid resultingin the fast reciprocation of the piston.

Other objects and advantages more or lessancillary to the foregoingreside in the specific construction and aggroupment of the elementspeculiar to this structure, as will become apparent from a more completeexamination of this specification.

In the drawing:

Fig. 1 is a longitudinal sectional view of a portion of a rock drillillustrating the invention.

Fig. 2 is a view similar to Fig. 1 illustrating movable parts in anotherposition.

Fig. 3 is a cross sectional view taken in a plane indicated by line 3-3in Fig. l.

Referring to the drawing, 18 represents a cylinder formed with a pistonchamber ll having a piston 12 reciprocable there-in for deliveringimpacts to the drill steel in the usual manner. Intermediate its ends,the cylinder H) is provided with the usual exhaust port It.

The rear end of the cylinder I is formed with a counterbore l4accommodating a valvular mechanism including a valve casing I5 havingmounted in the lower end thereof a valve cap it formed with an externalannular flange l1 resting on the bottom of the counterbore I4, and avalve bushing l8.

In the upper end of the counterbore I4 is mounted the usual rotationmechanism including a ratchet ring I9 resting on the valve bushing 18,within which ring is rotatably mounted the head 29 of a rifle bar 2!extending through the valve casing l5 into the piston l2 for operativeengagement with a corresponding nut (not shown). The head of the riflebar is maintained within the ring it? by a bearing plate 22 clamped onthe ring by a back head 23 which is rigidly secured to the cylinder illby two side bolts 24.

Within the back head 23, there is a rotatable throttle valve 25 formedwith a central bore 26 having motive fluid admitted therein from anysuitable source, which central bore is capable of communication with alarge recess 2'! provided back of the plate 22 through a throttle valveport 23 and a back head port 29;

Referring now more particularly to the invention, the valve cap it isprovided with a tubular portion 30 extending upwardly therefrom into thecasing I5 to end level with an annular valve seat 3| formedby the bottomof a counterbore or valve 5 chamber 32 provided in the lower end of thecasing !5. This valve seat is opposed to a similar seat- 33 provided onthe valve casing l6 adjacent the lower end of the casing l5. Theinterior of the tubular portion 36 is spaced from the stem 10 25 to forman annular inlet passage 34 opening into the rear end of the pistonchamber II. Internally of the valve seat 33, the bushing 45 is providedwith an annular recess 35 communicating with front inlet passages 36through radial 15 ports 3?. Leading from the enlarged recess 2! behindthe bearing plate 22 there is a plurality of motive fluid supplyingpassages 38 opening into the valve chamber .32 of the casing l5 via anannular groove 39, while the chamber 32 is "2 0 capable of communicationwith the rear inlet passage 3d through. an annular clearance orpassageway ifl provided between the tubular portion 3!] and the casingHi. In the valve chamber 32 is reciprocably mounted a sleevedike valveil slid 25 able on the tubular portion 39 and capable of end engagementwith the valve seats 3! and 33.

Theupper end: of the casing it is also counterbored to form a valvechamber 42, the bottom 33 of which constitutes a valve seat opposed to a3'0 similar valve seat 24 formed on the valve bushing, which bushing hasa tubular portion. 45 extending downwardly into the casing !5 in spacedrelation therewith to provide an annular passageway to opening into therear inlet passage: 34. Internally of the valve seat 34, the bushing isprovided with an annular recess i! opening into the inlet passage 3%through radial ports 48, while the valve chamber 42 is in constantcommunication with the motive fluid-supplying passages 38 through anannular groove 49. Reciprocably mounted within the chamber 42, there isa sleevelike valve 5 slidable on the tubular portion of the bushing 98and capable of end engagement with the valveseats 43 and M. 45

In the operation of the mechanism, if the parts are positioned as shownin Fig. l, motive fluid admitted into the throttle valve bore 26 willflow into the recess 27 through the ports 28 and 29 for supplying motivefluid to the passages 38, from where the fluid will flow into the valvechambers '32 and d2 via'the grooves 39 and 49 respectively. With thevalves positioned as shown in Fig. 1, from the chamber 32 the motivefluid will flow cverthe valve seat-Stintotheagroove 35 $5 and therefrominto the passages 36 via the radial ports 31. During the flow of themotive fluid over the valve seat 33, the fluid will act on the front endof the valve 4| for maintaining the valve in end engagement with thevalve seat 3|. With reference to the motive fluid in the valve chamber42, it will flow therefrom into the annular recess 41 and into the frontinlet passages 36 via the radial ports 48. In this instance, the motivefluid passing over the valve seat 44 will also act on the adjacent endof the valve 50 for maintaining the valve in engagement with the valveseat 43. The motive fluid thus admitted into the front inlet passages 36will flow into the front end of the piston chamber I l to act on thepiston l2 for driving it rearwardly. During its rearward stroke thepiston will first cover the exhaust port l3 thereby subjecting theatmospheric air within the rear end of the piston chamber I l tocompression resulting in pressure being exerted on the inner or adjacentends of the valves 4| and 50 tending to shift them in the position shownin Fig. 2. As the piston reaches the end of its rearward stroke it willuncover the exhaust port l3, thereby enabling the motive fluid from thefront end of the piston chamber II to exhaust through the port 13 andcausing a consequential drop of pressure of the motive fluid to takeplace in the valve chambers 32 and 42, resulting in a drop of pressureon the remote ends of the valves causing them to shift to the positionshown in Fig. 2.

In this new position of the valves, motive fluid from the valve chamber32 will flow into the rear inlet passage 34 via the annular passage 40,thereby exerting pressure on the end surface of the valve 4! adjacentthe valve seat 3| for maintaining the valve in end engagement with thevalve seat 33. Simultaneously the motive fluid in the valve chamber 42will flow therefrom, via the annular passage 46, into the rear inletpassage 34 and will also exert pressure on the end of the valve 51!adjacent the valve seat 43 for maintaining the valve in end engagementwith the valve seat 44. vThe pressure fluid now flowing through the rearinlet passage 34 will be admitted into the rear end of the pistonchamber I l for driving the piston l2 downwardly. During its downwardstroke, the piston will first cover the exhaust port l3 and thereaftersubject the atmospheric air within the front end of the piston chamber Hto compression, thus resulting in pressure being exerted on the remoteends of the valves 4| and lil) tending to shift the valves into theposition shown in Fig. 1. As the piston reaches the end of its forwardstroke, it will uncover the exhaust port l3, allowing the motive fluidwithin the rear end of the piston chamber III to exhaust through theport l3 and thereby causing a consequential drop of pressure of themotive fluid on the ad jacent ends of the valves 4| and 5| resulting inthe valves shifting into the position shown in Fig. 1.

From the foregoing explanation, it will be understood that the presentconstruction offers a double supply of motive fluid into the front andrear ends of the piston chamber II. The front supply taking place whenthe valves 41 and 50 are maintained in spaced relation with the valveseats 33 and 44 respectively and the rear supply taking place when thevalves are maintained in spaced relation with the valve seats 3| and 43,thereby enabling a very short travel of the valve without restrictingthe admission of the motive fluid into the piston chamber l 1.

Although the foregoing description is necessarily of a detailedcharacter, in order to completely set forth the invention, it is to beunderstood that the specific terminology is not intended to berestrictive or confining and it is to be further understood that variousrearrangements of parts and modifications of structural detail may beresorted to without departing from the scope or spirit of the inventionas herein claimed.

I claim:

1. In a fluid actuated rock drill, a cylinder having a piston chamberand a piston reciprocable therein, an exhaust port for the pistonchamber, a valve casing, a pair of coaxially disposed reciprocatoryvalves longitudinally spaced within said casing, means for admittingmotive fluid into said piston chamber including an inlet passage leadingfrom one end of one of said valves to the rear end of said chamberthrough the other of said valves, a motive fluid supplying passagewayleading to said valves, and valve seats within said casing engageable bysaid valves for controlling communication between said passage andpassageway.

2. In a fluid actuated rock drill, a cylinder having a piston chamberand a piston reciprocable therein, an exhaust port for the pistonchamber, a valve casing, a pair of reciprocatory valves coaxially andlongitudinally spaced within said casing, means for admitting motivefluid into said piston chamber including a front inlet passage leadingfrom the remote ends of said valves to the front end of the chamber anda rear inlet passage leading from the adjacent ends of said valves tothe rear end of said chamber, a motive fluid supplying passagewaycapable of communication with said inlet passages, and valve seatswithin said casing engageable by said valves for controllingcommunication between said passages and passageway.

3. In a fluid actuated rock drill, a cylinder having a pistonreciprocable therein, an exhaust port for said cylinder, a valve casingformed with a pair of coaxially disposed longitudinally spaced valvechambers, means for supplying motive fluid to said chambers, front andrear inlet passages leading from each chamber to the ends of saidcylinder, a sleeve-like valve reciprocable within each of said chambers,opposed valve seats within each valve chamber engageable by said valvesfor controlling communication of said chambers with said front and rearinlet passages, the end surfaces of said valves forming valve actuatingareas subjected to pressure conditions Within said cylinder for shiftingsaid valves into operative engagement with one or the other of theirrespective valve seats, and holding areas for said valves also formed bysaid end surfaces subjected to motive fluid flowing into said passagesfor momentarily holding said valve in said operative engagement.

4. In a fluid actuated rock drill, a cylinder having a pistonreciprocable therein, an exhaust port for said cylinder, a valve casingformed with a pair of coaxially disposed longitudinally spaced valvechambers, means for supplying motive fluid to said chambers, a front anda rear inlet passage both leading from said chambers to the ends of saidcylinder, a sleeve-like valve reciprocable within each of said chambers,the adjacent ends of said chambers forming valve seats engageable bysaid valves for controlling communication between said chambers and saidrear inlet ports while the remote ends of said chambers form valve seatsengageable by said valves for controlling communication between saidchambers and said front inlet ports, and shifting areas on said valvessubjected to pressure conditions within said cylinder for shifting saidvalves into operative engagement with said valve seats.

5. In a fluid actuated rock drill, a cylinder having a pistonreciprocable therein, an exhaust port for said cylinder, a valve casingformed with a pair of coaxially disposed longitudinally spaced valvechambers, a front and a rear inlet passage both leading from saidchambers to the ends of said cylinder, the remote ends and the adjacentends of said chambers forming pairs of valve seats capable ofcommunication with said front and rear inlet passages respectively,means for admitting motive fluid to said valve seats, means forcontrolling communication of said valve seats with said inlet passagesincluding a pair of reciprocatory sleeve-like valves one within each ofsaid chambers, and shifting areas on said valves alternatively subjectedto pressure conditions within said cylinder for efiecting concurrentengagement of said valves alternatively with the inner and remote seatsof their respective chamher.

6. In a fluid actuated rock drill, a cylinder having a pistonreciprocable therein, an exhaust port for said cylinder, a valve casingformed with a pair of coaxially longitudinally spaced valve chambers, apair of longitudinally spaced valve seats within each of said chambers,a sleeve-like valve for each of said chambers reciprocable between saidseats, passages for admitting motive fluid into said chambers andtherefrom into the ends of said cylinder, said valves being capable ofconcurrent end engagement with the inner adjacent seats and subsequentlywith the remote seats within said chambers for controlling admission ofthe motive fluid into the cylinder, and opposed actuating areas on eachof said valves alternatively subjected to pressure conditions withinsaid cylinder for actuating said valves.

WILLIAM A. SMITH, JR.

